use proc_macro2::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput};
use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
pub fn enum_message_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
let name = &ast.ident;
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let variants = match &ast.data {
Data::Enum(v) => &v.variants,
_ => return Err(non_enum_error()),
};
let type_properties = ast.get_type_properties()?;
let mut arms = Vec::new();
let mut detailed_arms = Vec::new();
let mut serializations = Vec::new();
for variant in variants {
let variant_properties = variant.get_variant_properties()?;
let messages = variant_properties.message.as_ref();
let detailed_messages = variant_properties.detailed_message.as_ref();
let ident = &variant.ident;
use syn::Fields::*;
let params = match variant.fields {
Unit => quote! {},
Unnamed(..) => quote! { (..) },
Named(..) => quote! { {..} },
};
{
let serialization_variants =
variant_properties.get_serializations(type_properties.case_style);
let count = serialization_variants.len();
serializations.push(quote! {
&#name::#ident #params => {
static ARR: [&'static str; #count] = [#(#serialization_variants),*];
&ARR
}
});
}
if variant_properties.disabled.is_some() {
continue;
}
if let Some(msg) = messages {
let params = params.clone();
let tokens = quote! { &#name::#ident #params => ::std::option::Option::Some(#msg) };
arms.push(tokens.clone());
if detailed_messages.is_none() {
detailed_arms.push(tokens);
}
}
if let Some(msg) = detailed_messages {
let params = params.clone();
detailed_arms
.push(quote! { &#name::#ident #params => ::std::option::Option::Some(#msg) });
}
}
if arms.len() < variants.len() {
arms.push(quote! { _ => ::std::option::Option::None });
}
if detailed_arms.len() < variants.len() {
detailed_arms.push(quote! { _ => ::std::option::Option::None });
}
Ok(quote! {
impl #impl_generics ::strum::EnumMessage for #name #ty_generics #where_clause {
fn get_message(&self) -> ::std::option::Option<&str> {
match self {
#(#arms),*
}
}
fn get_detailed_message(&self) -> ::std::option::Option<&str> {
match self {
#(#detailed_arms),*
}
}
fn get_serializations(&self) -> &[&str] {
match self {
#(#serializations),*
}
}
}
})
}